What instrument did Mozart write for that was invented by Benjamin Franklin?

The answer to this is a Glass Harmonica. This is also an instrument called Glass Armonica. This is known to be a very expensive instrument so people would not purchase it unless they really want it. The inspiration for the creation of this instrument is actually musical glasses. When Franklin heard it, he realizes that he can create something that is more exquisite with a better sound.

There are about 50 glass bowls that are placed in a glass harmonica and the rotating spindle will be able to play them properly. If you do not know yet how this is played, you simply need to think about the sound that you make with a wine glass when you stroke its rim.